PreScheme: Low-Level Scheme Programming

• Reminder about the EmacsConf 2024 Call for Participation:

  The conference will be December 7 and 8 this year:

  https://emacsconf.org/2024/cfp/

  If you have an Emacs-related topic you're excited about, consider submitting a proposal!

• Next week: New System Crafters video on workflows for managing many tasks with Org agenda bulk actions!

• https://prescheme.org/
• https://prescheme.org/posts/announcing-the-pre-scheme-restoration.html
• https://en.wikipedia.org/wiki/Scheme_48
• https://s48.org/

We'll experiment with PreScheme by referring to the Scheme48 manual:

https://tailcall.au/s48-refman/scheme48.html

A good starting point:

https://tailcall.au/s48-refman/scheme48.html#Example-Pre_002dScheme-compiler-usage

C function interface:

https://tailcall.au/s48-refman/scheme48.html#Pre_002dScheme-access-to-C-functions-and-macros

Can we write a small program with Raylib using PreScheme?

• https://www.raylib.com/
• https://codeberg.org/FluxHarmonic/flux-chibi/src/branch/master/lib/raylib.stub

Not fully working, but close!

game.scm:

(define init-window (external "InitWindow" (=> (integer integer (^ char)) null)))
(define set-target-fps (external "SetTargetFps" (=> (integer) null)))
(define begin-drawing (external "BeginDrawing" (=> () null)))
(define end-drawing (external "EndDrawing" (=> () null)))
(define close-window (external "CloseWindow" (=> () null)))
(define window-should-close? (external "WindowShouldClose" (=> () boolean)))

(define-record-type color <color>
                    (make-color r g b a)
                    (r char color-r)
                    (g char color-g)
                    (b char color-b)
                    (a char color-a))

(define (main)
  (init-window 1024 768 "Hello from PreScheme!")
  (let loop ()
    (if (eq? (window-should-close?) #f)
        (begin
          (begin-drawing)

          (end-drawing)
          (loop))
        0)))

packages.scm:

(define-structure pstest (export main)
  (open prescheme
        ps-record-types)
  (files game))

compile.scm:

(prescheme-compiler 'pstest '("packages.scm")
                    'pstest-init
                    "main.c"
                    '(header "#include <raylib.h>"))